1. FIELD OF THE INVENTION
This invention relates broadly to article sterilization and sterile article storage technologies. More specifically, this invention relates to the sterilization of ophthalmic lenses and lens storage containers during contact lens production or packaging processes.
2. DESCRIPTION OF THE RELATED ART
Disinfection and cleaning methods are essential to the contact lens field. The patient or contact lens consumer commonly performs the disinfection process using self-contained over-the-counter disinfection products. A wide variety of contact lens disinfection methods which are directed to over-the-counter products have been disclosed in the literature and in patents.
For example, the use of hydrogen peroxide to disinfect contact lenses is well known. The hydrogen peroxide is typically decomposed after lens disinfection by a catalyst, such as the platinum catalyst disclosed in U.S. Pat. No. 3,912,451, issued to Gaglia. One example of a highly successful commercial hydrogen peroxide-based disinfection system designed for over-the-counter sale is the AOSEPT.RTM. disinfectant, cup, and disc, produced by CIBA Vision Corporation. While a wide variety of other patents have issued in the area of hydrogen peroxide lens disinfecting processes, there exist other methods for user disinfection of contact lenses.
A number of other disinfection processes have been disclosed in the art. For example, the boiling of contact lenses has been employed as a consumer-used disinfection method. However, boiling requires electrical power, which is a serious disadvantage because of consumers' convenience concerns. Another consumer-operated lens disinfection method involves the use of ozone, a known bactericide.
For example, U.S. Pat. No. 4,746,489, issued to Arnold, discloses a device and method for consumer disinfection of contact lenses with ozone. The method involves producing ozone by ionization, causing the ozone to migrate across a filter membrane, and causing the ozone to diffuse into an isotonic solution for soaking the lenses. The lenses are soaked on the order of two hours in the Arnold device. The Arnold device and method are claimed to be advantageous over other consumer products in the simplicity and absence of undesirable side effects.
U.S. Pat. No. 5,082 558 issued to Burris, also discloses a device and method for consumer disinfection of contact lenses. The disinfection device includes a chamber for containing a contact lens submerged in a liquid, a generator for producing ozone gas, a liquid circulation passageway, an output gas passageway, and a pumping system. Liquid is circulated through a junction, through which ozone is passed. The ozonated liquid is passed across the contact lens, then recirculated through the junction to repeat the ozonation step. The Burris disclosure indicates that this consumer-operated device is useful in improving contact lens hygiene as compared to other traditional consumer-operated disinfection methods.
With respect to sterilization processes useful in a manufacturing setting, European Patent Application No. 0 222 309 A1 discloses a process using ozone in which packaging material is disinfected. The process involves feeding an oxygen stream into an ozonating chamber, generating ozone from oxygen in the ozonating chamber, placing packaging containers in a sanitizing chamber, feeding the ozone into the sanitizing chamber, and purging the ozone from the sanitizing chamber with sterile air. The process requires that the ozone contact the packaging material for a predetermined time, followed by the sterile air purge step. The process is offered as an alternative to hot-sterilization, sterilization by application of electromagnetic radiation, or chemical agent sterilization.
Commercial contact lens manufacturing sterilization processes typically involve some form of temperature and/or pressure-based sterilization technique. For example, a hydrophilic contact lens is typically first formed by injecting a monomer mixture into a mold. The monomer mixture is then polymerized (i.e., the lenses are cured) by placing the mold in an oven over an extended time period. After other optional processing steps, such as quality inspections, the lens is placed in a container with a saline solution, and the container is sealed. The packaged lens is sterilized by placing the package in an autoclave at an elevated temperature and pressure for an extended period of time. Although this commercial process produces thoroughly sterilized contact lenses, the batch-wise autoclave sterilization step is time consuming and inefficient.
Although numerous consumer-oriented sterilization processes have been disclosed, there remains a need for a time-efficient, continuous, in-line production sterilization process. In addition, there is a need for a means of maintaining pharmaceutical, medical, and cosmetic products in a sterile environment during storage, absent the disadvantages associated with chemical additives.